The number of persons in the US population classified as obese (body mass index (BMI) of 30 kg/m2 or greater) has doubled in the past 25 years to approximately one-third of adult men and women. An additional 34% were overweight (BMI e25 but <30 kg/m2). Recently published studies suggest that periodontal disease prevalence is higher among obese persons compared to those who are overweight or ideal weight. However, all the studies on this association have been cross-sectional, making it impossible to determine if obesity has a causal role in the development or advancement of periodontal disease. A proposed model for the link is an inflammatory one in which pro-inflammatory cytokines produced by fat tissue interact with local cytokines produced in response to infection by oral pathogens. Diabetes and poor diet may also have key roles in the disease process. Prospective studies are now needed. This prospective study proposes to perform secondary data analyses of available oral health, body fatness, laboratory and dietary data from a unique cohort of 1,025 men who have been followed for more than 40 years in the Department of Veterans Affairs Dental Longitudinal Study. The men are not VA patients, but are volunteers who receive medical and dental care from the private sector. The first aim of the study is to determine if incidence of obesity increases the risk of periodontal disease incidence and progression, controlling for important confounding factors such as age, smoking and diabetes onset. Periodontal disease indices that have been measured on each tooth every 3 years in the cohort include alveolar bone loss from radiographs, probing pocket depth, and attachment loss. Multiple adiposity measures over the same time interval are available, including weight, body mass index, and waist and hip circumferences. Repeated measures of bio-electrical impedance analysis are available in a subset of 540 men. A second aim is to determine if weight loss impacts on subsequent periodontal disease risk and whether long-term changes in high sensitivity c-reactive protein, a marker of inflammatory status, are influenced more by changes in periodontal disease, weight (or %body fat) or impaired glucose tolerance. The third aim is to examine the further effects of dietary quality and variation in the interleukin and tumor necrosing factor- alpha genotypes on the obesity-periodontal disease association. Archived blood and serum samples will be analyzed for c-reactive protein and genotypes. The aims will be addressed with multivariate proportional hazards regression models that control for important confounders and examine interactions among the main predictors of periodontal disease. This proposed epidemiologic study is a timely and cost-effective means to help answer the questions of whether obesity increases the risk of periodontal disease and what are some like mechanisms. PUBLIC HEALTH RELEVANCE: The prevalence of obesity has doubled in the US population in the past 25 years. Recent cross-sectional studies suggest periodontal disease is more common in obese persons compared to normal or overweight. The findings from this prospective study in a cohort of older men will help determine if obesity is an independent risk factor that predicts the development or progression of periodontal disease.